1. Field of the Invention
The present invention relates to an integrated circuit with a memory incorporated therein.
2. Description of the Related Art
The inventors of the present invention know of an integrated circuit which is composed of a central processing unit (CPU), peripheral circuits associated with the CPU and a read-only memory (ROM) and fabricated on a single semiconductor chip. In the above-mentioned integrated circuit, the ROM is tested and the quality of the ROM is determined using the data obtained by comparing the data stored in and read out from the ROM with the data prepared beforehand.
However, in the above-mentioned integrated circuit, the data stored in the ROM is easily read out at a time when the ROM is tested, and as a result the data stored in the ROM can be readily analyzed by anybody and thus cannot be kept secret.